Process for gettering coils



Patented July 7, 193 1 UNITED STATES PATENT OFFICE DANIEL SNYDER GUSTIN, OF IBLOOMIIELD, NEW JERSEY, ASSIGIEI'OR TO WESTING- HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA PROCESS FOR GETTERING COILS No Drawing. Application filed May 11,

This invention relates to incandescent lamps and more particularly relates to a method of removing residual gases from the interior of said incandescent lamps through the use of suitable gettering materials and comprises essentially a method of introducing the gettering material into the incandescent lamp by applying the same in a dry adherent compactedstate to the lamp coil prior to mounting thereof.

In lamp manufacture it is necessary to provide within the evacuated glass chamber a material which will react and combine with theresidual gases contained therein. There is also incorporated therein and admixed with the active element an inert. material which will tend to volatilize and deposit upon the side walls of the glass envelope in such a manner as to absorb or break-up any volatilized deposit of the tungsten during the burning life of the device. Such comblned materials to effect this two-fold result are commonly .known as getters. In the lamp industry pend the admixed material ina so-called binder medium comprised essentially of a quick drying lacquer type such as amylacetate and nitrocellulose. The getter suspended in the binding medium is then a plied to the surface of -the lamp filament 1n any suitable manner, such as by dipping, brushing, spraying, etc.

YWith the development and general adoption of the coil typefilaments the difliculties ofapplying this type of getter material increased. The prior methods of applying the getter were directed to coating segmented type filaments and manufacturing difiiculties 1928. Serial No. 277,106.

were encountered in applying the same ters to the coil type filament. This resufiz eii in a decided increase in variability of life and maintenance, due to insuflicient or variable amounts of getter material within the evacuated incandescent lamps. The spraying method generally adopted in the gettering of coils is liable to cause a warplng or distortion oi the coil during the gettering process. 1

One of the disadvantages of the prior method of applying getters is therefore the non-uniformity thereby obtained in the operating life of incandescent lamps due to variations in the amount of the getter coating upon the wire. This is caused by unavoidable variations in the amount of binder material present in the mixture.

Another disadvantage is that in spite of precautions some of the red phosphorus in the getter-material becomes oxidized from the unavoidable moisture contamination in:

the amylacetate mixture, thus causing variable results. v I I A third disadvantage is in the subsequent inefi'ective removal of the binder employed from the metal surface prior to the exhausting of the lamp so that during, the operating 1 life of the lamp interaction occurs between the. decomposed organic ortion of the binder material and the metal lament.

Another disadvantage is the usual manufacturing losses in getter material encountered in manufacturing processes.

One of the objects of the present invention is to provide a method of introducing the getter material into coil type filaments whereby uniformity-in getter action is 'obtained.

Another object of this invention, is to provide a simple and efiective method of applying the getten to the coil type filament.

Another object of the invention is to increase the life and luminous efliciencyof the incandescent lamp. 4

Another object is to increase the uniformity in the operating efliciency of incandeseent lamps. Another object is to increase the manufacride content of the getter over that heretofore practical to apply by the prior processes. Through this increase in the cryolite content I am enabled thereby to increase the normal luminous eificiency of the incandescent lamp. By the practice of my invention Iflamjalso enabled to accurately control and increase or decrease at will the proportionate amounts of the red phosphorus in the gettermaterial, thereby increasing the efficiency of the exhaust with beneficial results upon the normal operating life of the.

incandescent lamp.

nitrocellulose or other binder material from the getter I am enabled to increase thereby the exhaust efliciency during the manufac turing process and in addition remove the deleterious effects of the use of the binder upon the phosphorus content of the getter and uponthe subsequent variable clean-up action of the getter materialon the residual gases. I am also thereby enabled to normally decrease the amount of the phosphorus necessary to use in effecting substantial clean-up of residual gases 1n the evacuated v lamp, thereby effecting an appreciable savings in production costs while increasing manufacturing efliciency. By the use of a dry method of gettering I am also enabled 'to effect an increase in production efliciency and a decrease in production losses in manufacture, caused by inexpert handling of the getter and filament. v I

In the practice of my invention I take the usual getter materials, such as cryolite and red phosphorus in the desired proportions, and finely comminute the admixed material in a ball mill in any suitable manner, as by dry milling or by milling under a. fluid, such as alcohol, which may subsequently be removed by'evap oration and which is non-reactive towards the getter ingredient. The degree of comminution obtained can best be described as being finely subdivided to the pointwhere the material packs almost from its own weight. At. the conclusion of the ball milling procreadily,

ess the finely comminuted material is placed in anflair tight container. Thereafterthe coiled filaments, prior, to mounting in the incandescent lamp, are placed in the same container and the two are vigorously shaken together or admixed.

By the elimination of the amylacetate v The finely divided getter material is thereby forced into the interstices and between the windings of the coiled filament and retained there; To assist in this mechanical packing process it is permissible to employ as an added constituent of the getter, a dense heavy metal in particle sizes su cient to prevent the same from being itself forced between the interstices in the coils but dense enough to provide packing weight upon the getter material. I have successfully employed zinc in shot in granulated form for-this purpose, preferably as this metal also is an effective clean-up agent and if during the shaking process finely divided particles of the zinc should become detached, such particles would not thereafter become detrimental but beneficial in the subsequent clean up of residual gases of the incandescent lamp, by Y vaporization from the filament.

At the conclusion of the packing process, the coils may be separated from the excess getter material by sieving through a coarse screen. The excess getter is then returned to an hermetically sealed container for future use. A coiled filament is considered'gettered when the core and spaces between the turns of the coil are completely filled with the getter.

The gettered coils may thereafter be mounted in incandescent lamps in the usual manner and will withstand considerable rough handling without'loss of the getter material or distortion of the coil.

Incandescent lamps made using coil type filaments gettered by my process showed an appreciable increase in life, efficiency and maintenance over those made by the wet or spray method;

In addition, however, the manufacturing efiiciency through the use of my process permlts 1n large savings of time, materials and reduces those manufacturing losses due to inexpert handling, and furthermore, produces a unlformity in gettered product not heretofore obtained-by prior processes. Havmg described my invention, it is apparent that many methods ofapplying the getter in a dry manner to the coil without essentlally departing from the nature of the invention will occur to those, skilled in the art, but-such departures and variations are antlclpatedas may fall Within the followmg claims.

What is claimed is:

1. The method of gettering a coiled filament comprising mechanically compacting finely divlded dry getter material within the (3011s of the said coilfilament.

2. The method of gettering a. tubular filament'. which comprises mechanically compactmg a core of the finely divided dry getter within the said filament.

3. The method of gettering coil type filato effect mechanical compaction of the dry therein a'core of finely divided dry getter material.

4. Anarticle of manufacture comprising 7 a coiled filament having a mechanically compacted core of dry, pulverulent getter material.

5. The method of gettering coil type filaments which comprises forming a finely divided pulverulent dry getter material, adding thereto a proportion of granular particles of metallic zinc, the individual size of said granules being. substantially greater than the size of the interstices of said coil type filaments, incorporating therewith the c011 type filaments to be gettered, enclosing the whole admixture in a sealed container, and vigorously agitating the container and contents to effect mechanical compacting of the dry pulverulent getter within the coil core of the coil type filament.

6. The method of gettering coil type filaments which comprises commlnuting the getter composition to a finely ,divided pulv'erulent form, drying said getter, incorporating. therewith the unmounted coil type filament Y to be gettered, enclosing said mixture in a sealed container, and vigorously agitating the container and contents to effect mechanical compaction of the dry pulverulent getter material within the interstices of the coil as a result of the kinetic energy developed by the agitated coils and' getter material within the container.

7. The method of gettering coil type filaments which comprises finely comminuting the dr getter material, admixing therewith coarse y granular particles zinc, incorporating therewith the unmounted coil type filaments to be gettered, enclosing the mixture in a sealed container and thereafter vigorously agitating the container and contents pulverulent getter material within the coil interstices as a result of the'kinetic energy developed by the agitated coils and getter mixture within the sealed container.

In testimony whereof, I have hereunto subscribed my name this 10th da of May 1928.

DANIEL SNYDE GUSTIN. 

